Correspondence among

Mike, In response to your letter dated 9/10/14 and our meeting on 11/07/14 please find attached a draft of the OER for your review and comment. Jeffrey R. Hansen Senior Project Manager Lockwood, Andrews & Newnam, Inc. RUE A DALY COMPANY 1311 South Linden Road, Suite B « Flint, MI 48532 T 810.820.2682 C 810.333.3201 www.lan-inc.com * [email protected] CONFIDENTIALITY AND PRIVILEGE NOTICE: This email communication, including any and all attachments, (collectively, this “Communication’), is intended solely for the person(s} to whom it is addressed. This Communication may contain information that is privileged, confidential and/or proprietary. Any unauthorized use, disclosure or copying of this Communication is strictly prohibited. If you have received this Communication in error, please contact the sender immediately and destroy any and all copies of this Communication. xxxEND_PAGE:deq04_b576_5666_6018_275 Operational Evaluation Report City of Flint ine Trihalomethane Formation Concern November. 2014 Lockwood, Andrews & Newnam, Inc. A ALEO-A-DALY COMPANY. xxxEND_PAGE:deq04_b576_5666_6018_276 CITY.OF. FLINT Operational Evaluation Report December 1, 2014 TABLE OF CONTENTS ~1. Detroit Water & Sewer Department. 25. Karegnondi \ Water Authority i Interim Period _3. Pump Stations —— __ ee 1 BL Operations & Maintenance : __. A A - 12 _. ‘Water System Hydraulic Modeling ; ; ; : AD A. Simulation. of - 12 2: 42 j Lockwood, Andrews Bape: lon & Newnam, Inc. A LEGA DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_277 CITY. OF. FLINT Operational Evaluation Report December 1, 2014 TABLE OF CONTENTS ~V, Recommendations to M i imize Future OL “Exceedances urce __ Operational Recommendations _ Infrastructure Change Recommendations str System 7 1. Manage ' Water Age_ a. Storage Tanks _ _b. Cast tron, Pipes _ . Booster Disinfection _ E. Categorization of Actions — _ VI, Figures 1, 2014 DBP Test Results wet 2002 WTP Treatment Recommend itions “43 13. 137 14 14 14. 15 15. 15_ 15 “15 15. “45 Page ii lon Lockwood, Andrews & Newnam, Inc. A LEO A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_278 CITY OF FLINT Operational Evaluation Report December 1, 2014 EXECUTIVE SUMMARY Environmental Protection Agency (EPA) and Michigan Department of Environmental Quality (MDEQ) regulations require that public water suppliers test drinking water quarterly throughout the distribution system for disinfectant by-products (DBP’s). Two categories of DBP’s, tri-halomethanes (THM) and halo-acetic acids (HAAS), are regulated and must be tested for. The City of Flint began operation of their water treatment plant (WTP) full time with the Flint River as the source on April 25, 2014. Since that time, two quarters of samples taken indicate that future violations are inevitable for total THM without some modifications to the water system. In response, the City hired Lockwood, Andrews & Newnam, Inc. (LAN) to complete this Operational Evaluation Report (OER) in conformance with EPA guidelines with the goal to determine the cause(s) of high levels of THM and evaluate possible solutions. The EPA promulgated the Stage 2 Disinfectants and Disinfection By-Products Rule (DBPR) in January 2006 which set maximum contaminant levels (MCLs), for total trihalomethanes (TTHM) and HAAS based on an annual running average,tested quarterly, for a given sampling location, The City of Flint reports levels from 8 sampling test locations. Of the two quarterly sampling cycles since Flint began operating the: Il time, HAAS levels have been acceptable but TTHM levels have been high at all:8. quarters of sampling data with the most current period counting twice. re, the tity of Flint has not yet experienced a violation of the TTHM MCL becai ly 2 quarters of data have been indica id of an MCL exceedance later this year. A number of issues have been identified measured. Hon i “hich has resulted in increased chlorine feed. ¢C reased chlorine demand. ing contributed to chlorine demand. distribution system contributing to chlorine demand. tribution system due to less than ideal configuration of side pump stations. stagnant water in some areas. High chlorine'de in filters, High THM form potential (THMFP) in source water. Less than optimal removal of THM precursors VPSyeN = GoM ACTION PLAN The City of Flint has signed an agreement with the Karegnondi Water Authority (KWA) to purchase raw water drawn from Lake Huron, The KWA system is currently under construction and expected to be operational by late 2016. The water supply from Lake Huron will have entirely different water quality characteristics from the Flint River and those characteristics are expected to yield drastically reduced DPB formation. With that, non- structural options to help reduce THM levels are much preferred over solutions requiring new construction. Therefore, two categories of actions have been devised: Stage 1 being actions that can be completed relatively quickly without major construction and Stage 2 consisting of either long term actions or solutions requiring major construction. The City has completed or intends to complete Stage 1 Actions by February 16, 2015, the week in which the next quarterly sampling is to be done. Stage 2 actions are to be implemented only if Stage 1 Page 1 of 16 Lockwood, Andrews & Newnam, Inc. A LEG A DALY COMPANY DALY COMPANY | | | | xxxEND_PAGE:deq04_b576_5666_6018_279 CITY OF FLINT Operational Evaluation Report December 1, 2014 actions are ineffective in adequately reducing TTHM levels and therefore Stage 2 is contingent upon the outcome of Stage 1. Stage 1 — Immediate Actions ¢ Hire ozone system manufacturer to troubleshoot ozone system ¢ Bench scale jar testing © Match existing process and access possible areas of improvement o Simulate potential modifications to treatment process o Evaluate coagulation and flocculation polymer aid feeds to assist with TOC removal © WTP operational changes o Discontinue softening bypass stream to reduce chlorine demand o Disinfection of filter beds to reduce chlorine dei o Possibly begin coagulation and flocculation pe TOC removal depending on bench scale test, ¢ Increase water main flushing efforts to minimize stagnant water er aid feeds to assist with d potential solutions Storage tank volume use Possible broken closed valve locatio! Locations in need of flushi Lower high water levels in o0000 Stage 2 — Contingent Actigi Fix ozone system nd flocculation polymer aids to lower TOC, if not Increased main flushing based on water modeling results Continue valve replacements with water model assistance Emphasize cast iron pipes on water main replacement priority list eeeee3¢ese =| = bse) —- @ of ie} ao] =a 3. N 3 = ° N ° 2 fo) o ee =. o o =. iS = Page 2 of 16 Lockwood, Andrews &Newnam, Inc. ® LEG A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_280 CITY. OF FLINT pats Operational Evaluation Report as December 1, 2014 I. BACKGROUND The City of Detroit Water and Sewer Department (DWSD) has historically provided drinking water for the City of Flint and Genesee County. In the late 1990's growing concern regarding the reliability of the DWSD supply prompted the City of Flint to upgrade their existing water treatment plant (WTP). Those improvements, defined as Phase |, were completed in 2005 and were intended to allow the Flint WTP to operate, using the Flint River as the source, for an extended period of time in the event that supply from the DWSD was temporarily interrupted. Additionally, the Phase | improvements set the stage for Flint to break free from dependence on the DWSD supply and water charges over which they had no control. A. WATER SUPPLY TRANSITION 1. Detroit Water and Sewer Department (DWSD) Until recently the Genesee County and Flint region had been provided drinking water by the DWSD. However, due to excessive cost increases and reliability issues with the DWSD system other options had to be explored 2. Karegnondi Water Authority (KWA) In 2010 the Karegnondi Water Authority developing a new water supply from Laké region in lieu of the DWSD supply and the City of Flint elect he KWA expects the new system which is currently being constructed to become operational in the fall of 2016. > méd for the purpose of 3. Flint River — Interim Period With a renewing water supply ai terminated by the DWS' expected to be operati rt 016, the City of Flint decided to initiate tilizing the Flint River as the interim water ere necessary for the Flint plant to become report, Phase ll improvements to the Flint WTP e been made to allow the plant to operate full time with e or the KWA supply as the source. source. A variety of V a full time plant. For p' are improvem either the Fl B. TTHM PEND The calculation for de ning if the MCL has been violated for TTHM is: (2 x current quarter value + previous 2 quarter values) / 4 Flint has completed tests for 2 quarters and therefore has not violated an MCL limit to date. However, the third quarter of sample data is likely to provide MCL exceedances at all 8 sampling sites. Test results are tabulated below. Lockwood, Andrews Page 3 of 16 Ke] p) & Newnan, Inc. A LEO A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_281 CITY. OF FLINT Operational Evaluation Report December 1, 2014 TABLE 1.— 2014 DBP TEST RESULTS 1) 3719 Davison - McDonalds 2) 822 S. Dort Hwy - BP Gas Sta. 3) 3302 S. Dort Hwy — Liquor Pal. 4) 3606 Corunna — Taco Be 5) 2501 Flushing — Univ. Market 38 17 6) 3216 MLK — Salem Housing 41 25 7) 5018 Clio — Rite Aid 49 30 8) 6204 N, Saginaw — N. Flint Auto 50 37 TTHM MCL = 80 ug/l HAAS MCL = 60 ug/l C. WATER TREATMENT PLANT RECENT IMPRO 1. Phase I WTP Improvements Since 1965, the Flint WTP has remained > DWSD primary supply. Typically the seco expected to be needed only durin rersency uations and normally is designed for Conversely, Phase | improvements \ WTP in order to allow for an exte vort term aried (6 weeks) because of the would fail and remain out of service for an extended duration. R plant and as such é provements a treatability study was completed by n, LLC (AB&H) in 2002. The Treatability Study evaluated Point of Dosage : : Purpose Application (mg/l) Soden erage Zebra mussel control Intake 0.3 Ozone Taste & odor removal, disinfection Turbidit & TOC removal Rapid mix 2.0 Turbidity & TOC removal Floc basin 0,05 | Softening Softening basin 175 Ferric chloride Floc aid polymer Lime | | | Diffusor basin 1.5 | Soda ash Softening Softening basin 52 Carbon dioxide H_ adjustment Recarb basin 37 Media filters Filtration Na Na Chlorine { Disinfection | Filter effluent {__1.0 Lockwood, Andrews Page 40016 Kp] &Newnam, Inc. A&A CEO A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_282 CITY OF FLINT. Operational Evaluation Report December 1, 2014 Of the recommended items, zebra mussel control, coagulant and flocculation polymer aids, and soda ash feed have not been incorporated into the treatment process. 3. Phase Il WTP improvements for Full Time Operation Phase Il WTP improvements are those needed to convert the Flint WTP from a back- up supply to a primary supply plant. A number of improvements have already been constructed as they were necessary to operate full time, treating water from the Flint River, The improvements under the title of Phase Il that have been completed or are nearly complete include upgrades to the lime sludge lagoon, the lime sludge lagoon decant and disposal system, decant pump station and force main, installation of mid- point chlorination before filtration, and upgrade of the electric feed sub-station. Additional improvements to the Flint WTP that are to be completed to become part of the normal treatment process using water supplied by thed<WA are: « New oxygen and nitrogen storage facilitie: he ozone system (under construction) ¢ New coagulant feed system e Electrical o Pump Station #4 upgrades (under o SCADA and controls upgrades o Filter transfer pump station \ feeders e Installation of the future raw water construction) : * Pump replacements lation in the low and high service pump station (under constry Lockwood, Andrews Page 5 of 16 ja Nn & Newnam, Inc. ALEOQA A LEO A DALY COMPANY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_283 CITY.OF FLINT Operational Evaluation Report December 1, 2014 Il. SOURCE WATER EVALUATION A. DATA ANALYSIS Based on past data collected and the 2002 Treatability Study by AB&H, the Flint River water quality varies seasonally with higher hardness and alkalinity experienced in the winter. Higher magnesium concentrations are also experienced in the winter, adding difficulty to the settling process due to neutrally buoyant floc. General water quality average characteristics recorded for the 2002 Treatability Study as compared with average characteristics recorded this year are shown in Table 3 below. TABLE 3 — FLINT RIVER WATER QUALITY CHARACTERISTICS : : Hardness Turbidity | TOC | Alkalinity Total Col. NTU |. Mell A Mgi/l ; : “| Count/day. 870-1230 (7300 max) 1900-9000 (48,300 max) 7.9 9.4 10.3 5/22/14 215 investigation by City staff revealed significantly over the past 10+ years. Note tha’ ibuted to the total Coliform count. a sewer leak upstream of the plant that may have The leak was subsequently repaired. B, CONCLUSIONS Considering the minor ch Fi ver water quality, much of the information contained in the 2002 Treatabili &H remains relevant today. Data from that ly with higher hardness and alkalinity in the winter kalinity, magnesium concentrations tend to be reduced by run-off ikely?380-440 micrograms per liter as measured between April . The City intends to re-test the raw water to confirm the ‘ed. Results are pending. 2001 and Jan THMFP has not In development of the 2002 Treatability Study, processes were simulated which resulted in low THMFP. Therefore, information contained in that report will be used to assist with establishing a baseline jar testing procedure as discussed further in Section III. Lockwood, Andrews Page 6 of 16 Kp] & Newnam, Inc. RLEG A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_284 CITY OF FLINT Operational Evaluation Report December 1, 2014 Ill, TREATMENT PROCESS EVALUATION A. EXISTING PROCESS DESCRIPTION The existing WTP consists of an intake with screening from the Flint River, low lift pumping, ozonation, rapid mix, flocculation, settling, softening, recarbonation, filtration, storage and high service pumping. A process diagram is shown as Figure 1. 1. Intake A 72” diameter pipe draws water from the Flint River through 2 traveling screens to the low lift pump structure. No chemicals are currently fed for Zebra mussel control or pre-oxidation as recommended by the 2002 Treatability Study. Manual removal of zebra mussels proved to be more economical than installation of chemical feed equipment considering the short term need. 2. Ozone There are 2 ozone generators designed to provide ad up to 36 mgd. There are 3 ozone contact b designed to produce 900 Ibs/day at 10% con concentration each. Recent readings approximately 700 Ibs/day at 4% concent ate ozone for a WTP flow of e ozone generators were to 1300 Ibs/day at 6% =,production rate of the purposes of taste current ozone feed might not be optimized to realize additional TOC removal: benefits demonstrated by previous tests. Also, less than optimal ozonation h i ed chlorine feed. 3, Rapid Mix East and West rapid mi ‘ basins. Each rapid mix iberyi ed with a 5 hp mixer. The WTP contains two fall locculation basins, east and west, and each basin provide: ] adually slowed mixing from inlet to outlet. There are Vebasin with VFDs to control mixing speed. The 2002 sd feeding both coagulation and flocculation polymer is being used today because turbidity and TOC removals t to meet regulatory requirements. have been suff 5. Settling Primary clarification takes place within 3 basins containing plate settlers. The settlers are operating as designed. 6. Softening Again, there are two basins for softening: east and west. Each basin is 120’ in diameter and contains a solids contact softening unit. Each softening basin/unit has a design capacity of 18 mgd. Low lift pumping limitations, flow control to the basins, and fluctuating demands have made it difficult for WTP staff to stabilize the softening process. Softening is accomplished by feeding lime. The decision was made by the City not to feed soda ash in order to remove non-carbonate hardness because acceptable hardness levels could be achieved with lime feed only and softening is short term until Lake Huron water becomes available. Lockwood, Andrews Page 7 of 16 lon & Newnam, Inc, A LEO A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_285 CITY OF FLINT Operational Evaluation Report December 1, 2014 7. Recarbonation Recarbonation for pH adjustment is accomplished in east and west recarbonation basins between and to the north of the softening basins. Carbon dioxide storage and feed equipment is located west of the recarbonation basins. 8. Filtration Filtration is accomplished with 12 dual media filters, equally sized and designed to filter 3.0 mgd each. Media consists of 12” of sand and 18” of anthracite. The filters have been operated intermittently over the years due to the standby nature of the WTP and until recently, chlorine injection took place downstream of the filters. It is possible some microbial growth has developed in the filters. 9. Disinfection Limited disinfection is provided by ozonation, but the primary form of disinfection is chlorine fed prior to filtration and prior to finish water storage / high service pumping. The intermediate chlorine injection location was reéently constructed under the Phase II, Segment 1 contract. x 10. Clear Well & Pumping The pump building sits adjacent to a 3 M high service pumps. gntains both low and B. JAR TESTS / EXPERIMENTS 1. Approach There are several well practiced met disinfectant can be changed.to an al Second, additional treatment 4ys' (depending on the nat Lastly, the existing t precursor as possible. only strategy thats re oe es has a lower tendency to form DBPs. te uch as activated carbon or air stripping ce s) can be added to remove DBP precursors. 1 Pioeesses ‘an be optimized to remove as much DBP options, optimizing existing treatment processes is the quire the construction of new and expensive facilities. It receiving Lake Huron water in approximately two ‘a completely different chemistry from the Flint River. tituted to address THM levels using Flint River water are y’ for Lake Huron water and may even be inappropriate. Therefore, thos ns Which require addition of new treatment processes are undesirable at this time. In recognition of this upcoming change in water source, this study will concentrate on improving the existing processes, rather than adding new ones. New treatment processes will only be recommended if operational changes to the existing treatment train prove ineffective. Recent sample test results suggest that most of the DBPs are formed in the distribution system rather than within the treatment plant. Therefore, the most logical approach is to reduce the DBP formation potential (DBPFP) rather than simply lowering the levels of DBPs leaving the plant. During bench scale testing, formation potential (FP) levels will be the primary indicator of success or failure of any proposed process modifications. 2. Protocol Bench scale pilot testing is intended to reflect actual plant operating and hydraulic conditions so the bench scale treatment units will be sized based on various dimensionless factors to ensure the pilot treatment matches the actual system, Bench scale ozonation is not practical due to time and cost limitations. Therefore, water Page 8 of 16 Lockwood, Andrews & Newnam, Inc. WLEG A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_286 samples will be withdrawn following the plant ozone basin. These samples will be transported to the laboratory where they will be dispensed into square testing jars. The jars will act as rapid mix, three-stage flocculation, and settling. Rapid mix and flocculation conditions will be matched to the plant based on “Gt” values. The “G” value is a measure of the mixing intensity and is a function of mix time, viscosity of the liquid, and mixing power applied to the water. “Gt” then, is a size scaling factor where time has been accounted for. Settling time will be scaled to match the shorter settling depth of the testing jars. After settling, samples will be decanted from the test jars. The decanted samples will then be lime softened; softening conditions will be similarly matched ‘on the basis of “Gt’. Fluoride will be added and carbon dioxide sparged into the samples to reduce the pH. The water will then be vacuum filtered through filter paper, sized to simulate the plant's dual media filters. The samples will be dosed with excess chlorine and allowed to react for seven days before testing for DBPs to determine the formation potential. Although these conditions may be refined based on new information, we anticipate the following: TABLE 4—- BENCH SCALE TEST. MIXING INTENSITIES _ Process _ ‘Duration Cecaation : Rapid Mix 25 sec Flocculation, Stage 1 9 min Flocculation, Stage 1 9 min Flocculation, Stage 1 9 min Settling 10 min Softening 10 min Recarbonation na and chemical dosag conditions wi Lockwood, Andrews Page 220816 Ks] p) &Newnam, Inc. A’ (EO A DALY COMPANY ~ Current Usage 2002 Study Ozonatie 4.66 mg/l 1.5 mg/l Ferric Chlofi 7.7 me/l 40 mg/l Coagulant Aid Polymer Not used 2.0 mg/l Flocculation Aid Polymer Not used 0.05 mg/l Lime 120 mg/l 175 me/l Soda Ash Not used 52 mg/l Cationic Softening Polymer Not used Anionic Softening Polymer Not used Fluoride Carbon Dioxide g Chlorine 6.3 mg/l 1 mg/l _| xxxEND_PAGE:deq04_b576_5666_6018_287 CITY OF FLINT Operational Evaluation Report December 1, 2014 3. Considerations The 2002 Treatability Study did not note significant formation of DBPs. This may be a function of different Flint River water chemistry at that time. However, recognizing the considerable differences in chemical usage and dosages between that study and current operations, those differences in chemical use and dosage are an obvious starting point for optimizing treatment to prevent DBP limit exceedance. Although it is believed that optimization of current treatment can correct the DBP issue, should optimization of present treatment prove insufficient, alternate residual disinfectants (chloramines and chlorine dioxide) will be investigated as additional treatment measures, 4. Results [To be completed following jar testing and experimentation] 5. Conclusions {To be completed following jar testing and experim: Lockwood, Andrews Page 10 of 16 or & Newnam, Inc, A LEO A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_288 CITY. OF FLINT. Operational Evaluation Report December 1, 2014 IV, DISTRIBUTION SYSTEM EVALUATION EPA guidance for the distribution evaluation portion of an OER is focused on identification and isolation of a specific portion of the distribution system that led to the exceedance. The circumstances of Flint’s apparent pending TTHM exeedances are unusual in that a new supply has been implemented which clearly corresponds to the high TTHM sample results. Despite obvious implications to the primary cause of increased TTHM levels, value remains in evaluating the distribution system as there may still be distribution improvements that can be made to help alleviate the problem. Evaluation of the distribution system, including modeling, was recently added to LAN’s scope of services. When finished, information will be provided to complete the following topics in this section. A. INFRASTRUCTURE 1. Piping According to the most recent MDEQ Sanitary estimated to contain 70% cast iron, 20% d e iron, water mains, Unlined cast iron pipe can beéome pitted, allowing colonization sites for microorganisms leading to chlorine d id. Additionally, much of the piping in the system is aged and in poor condit sed chlorine demand could be resulting from biofilm in older pipes and from breaks/repairs. e distribution system is concrete and 8% steel The City utilizes City Point softwar and prioritize replacements. Areas include Fenton Road, Ather Drive. The extent of ort Highway, Averil Street, and Boulevard t known but any water main replacement properly. 2. Storage 3. Pump Stations {To be completed] *® Condition © Pump capacity evaluation ¢ Valve condition and pressure zones OPERATIONS AND MAINTENANCE 1. Pump Station & Storage Operations {To be completed] * Control of pressure districts ¢ WTP Pump Station (No. 4) © Cedar Street Pump Station © Westside Pump Station Lockwood, Andrews Page 11 of 16 Kp] & Newnam, Inc. ALLO A DALY COMPANY | xxxEND_PAGE:deq04_b576_5666_6018_289 CITY OF FLINT Operational Evaluation Report December 1, 2014 * Torrey Road Pump Station ¢ High and low levels in tanks 2. Booster Disinfection Practices Booster disinfection is provided at the Cedar Street and Westside pump stations. Sodium hypochlorite is applied while the reservoirs are being filled. 3. Changes in System Demands {To be competed] e Long term decline in demands e Short term fluctuations — max day in winter due to high volume of main breaks C, WATER SYSTEM HYDRAULIC MODELING [To be completed] 1, Simulation of Existing System Match existing conditions, particularly chlo at plant and residuals at 10 locations in e. chlorine feed data 2. Identification of Deficiencies Specific issues to look at: Page 12 of 16 Lockwood, Andrews &Newnam,inc. *® LEG A DALY COMPANY LEQ A DALY COMPANY I xxxEND_PAGE:deq04_b576_5666_6018_290 CITY. OF FLINT Operational. Evaluation Report December 1, 2014 V. RECOMMENDATIONS TO MINIMIZE FUTURE OEL EXCEEDANCES A, SOURCE The City of Flint has already committed to the change from the Flint River as the water source to Lake Huron under the KWA system, planned for late 2016. The risk of future TTHM limit violations will decline substantially with the use of water from Lake Huron due to much lower DBP precursors. It is important to recognize that the Flint River will become strictly an emergency supply when the KWA supply becomes available and any investments toward the Flint River should be contemplated accordingly. Recommendations discussed below in this section apply to the Flint River as the source, Reverting to supply from the DWSD until the KWA supply is available as an option. However, the DWSD has stipulated that a $4 million connection fee would apply and current water rates would include approximately $900,000. month flat fee plus usage charges, Therefore, utilizing the DWSD for interim supply if cost prohibitive under the terms defined by the DWSD. 1. Watershed Management time. 2. Monitoring “ls, chara istics as part of standard preparation of Monthly Operating Reports,(MOR: Changes are recommended at this time. 3. Intake Operation The 2002 Treatabili permanganate as a permanganate _i j provided b' 2camamended pre-oxidation in the form of sodium ‘the“intake. However, pre-oxidation with sodium 4, Seasonal Past data ind Flint River is influenced by groundwater and in particular, dolomitic spring “Water. The result is hard water with high concentrations of magnesium and sulfate. Also, hardness and alkalinity are higher during the winter. Upon initiation of supply from the Flint River, the City made the decision to soften with lime only to focus on removal of carbonate hardness. One potential modification that could assist with TOC removal and thus decrease THMFP would be lime and soda ash softening. If implemented soon, the procedural change would be timely as it would also address increased hardness expected going into this winter. 5. Upstream Contamination Issues Upstream contamination issues are extremely difficult to prevent and even if detected are difficult to locate. Evaluation of raw water data collected for MORs is the easiest manner in which to detect upstream contamination issues because the data is already collected for treatment purposes. In fact, high total Coliform readings signaled a potential issue recently that the City identified and removed. An upstream monitoring and warning system could be established to attempt to detect spill event type contamination early enough to cease intake prior to the Lockwood, Andrews Page 13:09 16 on &Newnam, Inc. ALEO A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_291 CITY. OF. FLINT Operational Evaluation Report December 1, 2014 contamination reaching the WTP. However, given the imminent conversion to the KWA supply, the period of full time use would likely be far too short to achieve payback on the capital expenditures, B, TREATMENT PROCESS 1, Operational Recommendations ¢ Coagulation and flocculation _polymer_aids: The 2002 Treatability Study suggested the use of coagulation and flocculation polymer aids. These polymer aids were shown in the 2002 Treatability Study to increase TOC removal and thereby reduce THMFP. Further evaluation will be. completed during jar testing. e Discontinue softening bypass: The City was previously bypassing a portion of flow around the softening basins because hardness levels did not warrant softening of the full stream. However, this p e was discontinued because it was believed the bypass stream was conttibuting to chlorine demand and preliminary data has supported that belief” demand dropped 0.5 -— 1.0 mg/l following elimination of the b e Soften with lime and soda ash: Ri efficacy of this option will be evaluates Disinfection of filter beds:..In case ing jar testing. ‘e has been microbial growth it is / treated with chlorine and rinsed. A | | | tream of the filters during the first in the filters should not be an issue. atment processes: Depending on bench scale , ht modifications to all treatment processes JowerDPBFP. nents rema n in good condition and the system can be easily modified to restof Oper functionality. The City has scheduled the equipment manufacturer to field inspect the system on December 15, 2014. ¢ Change disinfectant to chloramine or chlorine dioxide: !f other options prove to be ineffective, conversion to another disinfectant should be fully evaluated. Various characteristics of chloramination indicate an advantage over chlorine dioxide, but a full analysis would provide clarity as to which would be preferred. ¢ Install_pre-oxidant chemical feed: Hydrogen peroxide as a pre-oxidant can enhance the activity of the ozone. This option is listed as a consideration only if problems continue with ozonation. e Repair upstream sewer leak: a sewer leak upstream of the WTP intake was discovered and has already been repaired by the City. Lockwood, Andrews Page 14 of 16 lon & Newnam, Inc. A LEO A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_292 CITY. OF FLINT. Operational Evaluation Report December 1, 2014 C. DISTRIBUTION SYSTEM Recommendations will be incorporated into this report when available. It is anticipated details will be provided for the following topics. [To be completed] 1. Manage Water Age a) Storage Tanks b) Residence Time in Pipes 2. Reduce Disinfectant Demand a) Flushing b) Cast Iron Pipes 3. Water Modeling of Recommendations Determine best flushing locations to reduce water age Changes to storage tank operating levels to reduce waté Evaluate booster disinfection f the distribution system. Water when freezing weather became the closed position and believed to A number of actions have already been taken‘in ter! main flushing efforts were increased until late ; prevalent. Also, numerous valves that were brokéi have been contributing to stagnant wa’ D. BOOSTER DISINFECTION ding booster disinfection in the distribution pe reaction time at higher concentrations of Considering that the Flint River is being used as the water source only until the KWA supply is available (expected late 2016), options to address high THM formation that require new construction or extensive time to implement are not preferred. On the other hand, the City understands THM sample results to date dictate that some action is necessary. Two categories have been developed to assist the City in prioritizing actions to take. Stage 1 consists of actions that can be completed relatively quickly without major construction and Stage 2 actions are either long term actions or solutions requiring major construction. Stage 1 actions are to be completed first followed by evaluation of the results prior to consideration of Stage 2 actions. Grouping of actions are shown in the table below. Page 15 of 16 Lockwood, Andrews &Newnam, Inc. ALEGA LEQA . DALY COMPANY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_293 CITY: OF FLINT Operational Evaluation Report December 1, 2014 _ Action TABLE 6 — ACTION PLAN Purpose Troubleshoot ozone feed system Reduce chlorine feed and increase TOC removal Bench scale jar testing Optimize treatment process and evaluate possible modifications Discontinue softening bypass Reduce chlorine demand Disinfect filters Reduce chlorine demand Increased water main flushing Reduce water age / stagnant water Water system modeling evaluation Determine areas with high water age and reasons “Stage 1 Implement coag. & floc. polymer aids, if appropriate Increase TOC removal __| Modify booster disinfection feeds, if | appropriate Repair ozone system Decrease water age | Reduce chlorine feed and increase TOC removal _ {Continue increased water main flushing Reduce water agi {Convert to lime and soda ash softening Increase TOC removal Continue valve replacements based on water model “Stage 2 Change disinfectant to chlorine dioxide Install pre-oxidant feed at intake _| Place priority on replacing cast iron __| water mains Samples were taken the week of Nové the City has begun implementation of Stage 4 be noticeably affected since there has ‘nat been” ied the third week in February. It is the City’s rior {6 the 3 quarter of THM sampling. quarter of sampling is due t intent to implement Stage 1 mpl 3" quarter of testing. Although HM results are not expected to ugh time for a response. The next Page 16 of 16 Lockwood, Andrews & Newnam, Inc. A LEO A DALY COMPANY xxxEND_PAGE:deq04_b576_5666_6018_294 i ! FROM FUNT ° RIVER — RAW WATER SCREENS INTERMEDIATE CHLORINE Genesee County OZONE SODIUM BISULFATE FERRIC CHLORIDE i = FLOW METER fe) M LOW LIFT OZONATION RAPID PUMPING MIX CARBON DIOXIDE FLUORIDE UME POLYMER _ (ANION & CATION) M FLOW METER RECARBONATION SOFTENING DUAL MEDIA FILTRATION CITY OF FLINT WATER TREATMENT PLANT REVISIONS THREE STAGE FLOCCULATION PLATE SETTLERS POST CHLORINE FINISHED WATER RESERVOIR (2) HIGH SERVICE . PUMPING WATER TREATMENT PLANT PROCESS DIAGRAM TO DISTRIBUTION — Project No. 130-10701-00t Dae Nov. 21, 2014 Sheet FIG 1 xxxEND_PAGE:deq04_b576_5666_6018_295 Rennaker, Joanne (DEQ)